The 49ers’ first three regular-season opponents – the Rams, Panthers and Seahawks – not only like to run the ball, they often do so with the help of a fullback.

That’s a concern when, since April, the 49ers’ defense has been practicing against new coach Chip Kelly’s offense, which prefers three receivers and one running back on the field and doesn’t even have a fullback.

That’s why Friday’s scrimmage with the Texans is so valuable. Houston also likes to run the ball with a fullback leading the way. The 49ers also host the Texans in Sunday’s preseason opener at Levi’s Stadium.

“For us defensively, it’s going to be huge from a player-evaluation standpoint and (because) it’s a totally different offensive scheme,” 49ers defensive coordinator Jim O’Neil said Thursday. “It’ll be a lot more two-back formations, stuff we need to see to get ready for the season. So it’ll be a big test for our defense.”

From 2003 through 2013, the 49ers held a joint practice with just one other team – the Raiders at their summer home in Napa. Since 2014, however, the 49ers have scrimmaged against the Ravens in Owings Mills, Md. and visited the Broncos practice facility outside of Denver.

This year, in addition to hosting the Texans, they’ll have back-to-back sessions next week with the Broncos at the defending Super Bowl Champions’ facility prior to the teams’ Aug. 20 preseason game in Denver. That’s the first time in recent memory the 49ers have scrimmaged two teams in one preseason.

“It’s a great way to gauge yourself,” said Kelly, whose Eagles also too part in scrimmages when he coached them. “I’ve done it in the past a couple times with the Patriots and once with the Ravens. We thought it was quality work in the three years that we did it.”

It helps when the coaches have a strong relationship, which Kelly has with the Texans’ Bill O’Brien.

They became acquainted in 1993 when Kelly was the defensive coordinator at Johns Hopkins and O’Brien was an assistant coach at Brown. They traded ideas and philosophies, which continued when O’Brien was on Bill Belichick’s staff in New England and invited Kelly, then at Oregon, to talk about his no-huddle offense.

“I’ve known Billy a long time,” Kelly said. “He’s a hell of a football coach, so we’re excited about that opportunity coming up.”

Their friendship has prompted plenty of communication between the teams. For example, O’Neil said he and Texans offensive coordinator George Godsey will exchange practice scripts before Friday’s session and will run specific plays or formations that will be valuable to the other team. They don’t play each other in the regular season.

“For me and George, it was more schematic stuff. ‘Hey, is there stuff that you’re not getting from your defense in Houston that you want to see?’” O’Neil said. “And I can emphasize some of that stuff in practice, and then it’s, ‘Hey, can you give us some of this because we’re not seeing this in practice to get us ready for the season?’ He’s been great. It’s been all good.”

Another benefit from the joint sessions: fresh opponents.

Friday’s practice should be especially valuable for someone like 49ers cornerback Jimmie Ward, who is playing a new position – outside cornerback – this season.

Most of Ward’s practice snaps have come against Torrey Smith, Quinton Patton and Bruce Ellington. Against the Texans, he’ll likely face wide receiver DeAndre Hopkins, who finished third in both catches (111) and receiving yards (1,521) last year.

“He’s pretty talented – a smart player,” Ward said. “I think it’s going to give me some good work heading into the season.”